Superparamagnetic iron oxide nanoparticles have been explored for uses in various medical applications, including, for example, MRI, hyperthermia therapy, and drug release systems. In MRI applications, superparamagnetic iron oxide nanoparticles have been investigated as contract agents and breast tumor imaging. In one study, nanoparticles that were modified with tumor targeting ligands (e.g., breast cancer cell surface receptor urokinase-type plasminogen activator) accumulated in mice breast tumors and generated strong contrast for imaging by clinical MRI (3 Tesla). In another study, targeted nanoparticles were used to detect circulating breast cancer cells in the blood, again using a mouse model.
In hyperthermia therapy, under median-level alternating magnetic field (AMF), magnetic nanoparticles can generate heat to induce breast cancer cell apoptosis. In one study, thermoablative therapy of breast cancer in mice was performed using antibody (mAb)-linked iron oxide nanoparticles. The magnetic nanoparticles were injected intravenously. The nanoparticles targeted human breast cancer xenografts in the mice, resulting in a delay in tumor growth after the AMF was applied.
Magnetic field drug release delivery systems have been investigated in the form of iron oxide loaded gels (e.g., gelatin, PVA), scaffolds, microbeads, composite membranes, nanoemulsions, silica nanocapsules or polymer nanoparticles. In one study, magnetic nanoparticles were bound with a chemotherapy drug and tested for targeted chemotherapy in a rabbit liver tumor model. Magnetic particles have also been investigated for both imaging and drug delivery in prostate cancer.
There is concern that pure iron oxide leads to acute toxicity. Further, due to anisotropic bipolar attraction, iron oxide nanoparticles may aggregate. The nanoparticles systems described above are based on encapsulated iron oxide nanoparticles to combat or mitigate aggregation and toxicity. The nanoparticles and any associated drug may be dispersed in oil/water and encapsulated by a multilayer polymer/liposome shell. However, heat conduction is relatively difficult with the multilayer shell as heat generated by the iron oxide must be transferred through the relatively low conductivity water/oil phase and then transferred to and through the polymer shell.
Accordingly room for improvement remains in the field of iron oxide nanoparticle formation and use, wherein the iron oxide particles may be more biocompatible, yet still transmit heat into surrounding matter.